It has been known for some time to equip data carriers, such as bank notes, papers of value, credit cards or ID cards or the like, with optically variable security elements, in particular optically variable diffraction structures such as holograms. Protection from forgery by holograms is based on the different optical impression of said holograms that occurs upon a change of viewing angle relative to the hologram. Said optically variable impression cannot be rendered by copying machines since copying machines only render the appearance of the hologram from a certain viewing angle. A data carrier with such a hologram is known for example from EP 0 440 045 A2. This print proposes applying the hologram to the data carrier as a prefabricated element or as an embossing in a lacquer layer applied to the data carrier.
However, there are other optically variable security elements that can be provided on a data carrier. Thus, it is known for example from CA 1 019 012 to provide a bank note in a partial area of its surface with a parallel printed line pattern. To produce the optically variable effect, a line structure is additionally embossed into the data carrier in the area of the printed line pattern so as to form flanks visible only at certain viewing angles. Selectively disposing the printed line pattern on like-oriented flanks of the embossed line structure causes the line pattern to be visible upon oblique viewing of the flanks provided with the lines. Upon oblique viewing of the rear side of the flanks the line pattern is not recognizable.
The antiforgery effect of such embossed optically variable security elements can be improved further if additional visually recognizable effects are produced by selectively changing the line pattern or embossed structure. Examples of such additional effects are described in WO 97/17211 and WO 02/20280.
The optically variable effect of the latter known security elements arises fundamentally from the combination of a print with a blind embossing that is preferably produced by intaglio printing. Blind embossing has the disadvantage that it cannot be integrated into a colored intaglio image but can only be used as an isolated security feature. This is because a relatively great distance between the blind embossing areas and the ink-carrying areas is required to make sure that absolutely no ink gets into the blind embossing depressions when the intaglio printing plate is inked.